Ok turn off Time Machine in System Preferences and then restart. Plug the drive in and open Disk Utility and Verify Disk on the external drive.
The problem with the Ext Hard Drive spontaneously ejecting itself stopped overnight but then resumed yesterday morning.
Any thoughts on how to prevent this from happening on a permanent basis.
The cable is integrated into the case that holds the Ext Hard Drive. I will replace the case and see if that does the trick.
I did replace the cable and the hardware that connects the Ext Hard Drive to my computer. Seems like it is working better.
Thanks for your help.